Language CDI Items N production N comprehension
Croatian 390 627 250
Danish 383 6112 2398
English 393 5967 1821
French 396 1364 537
Italian 396 1400 648
Norwegian 381 7466 2374
Russian 410 1805 768
Spanish 399 1872 778
Swedish 371 1367 467
Turkish 396 3537 1115
Example production trajectories for the words "dog" and "jump" across languages. Points show average proportion of children producing each word for each one-month age group. Lines show the best-fitting logistic curve. Labels show the forms of the word in each language.

Example production trajectories for the words “dog” and “jump” across languages. Points show average proportion of children producing each word for each one-month age group. Lines show the best-fitting logistic curve. Labels show the forms of the word in each language.

Predictor Highest Lowest
Babiness baby, bib, bottle donkey, penny, jeans
MLU when, day, store peekaboo, ouch, hello
Frequency you, it, that cockadoodledoo, grrr, church
Concreteness apple, baby, ball how, now, that
Solo frequency no, yes, what tooth, feed, aunt
Arousal naughty, money, scared shh, asleep, blanket
Length cockadoodledoo, refrigerator, rocking chair i, go, hi
Valence happy, hug, love sick, hurt, ouch
Final frequency book, it, there give, when, put
Estimates of coefficients in predicting words' developmental trajectories. Each point represents a predictor's coefficient in one language, with the large point showing the mean across languages. Larger coefficient values indicate a greater effect of the predictor on acquisition: positive main effects indicate that words with higher values of the predictor tend to be understood/produced by more children, while negative main effects indicate that words with lower values of the predictor tend to be understood/produced by more children; positive age interactions indicate that the predictor's effect increases with age, while negative age interactions indicate the predictor's effect decreases with age.

Estimates of coefficients in predicting words’ developmental trajectories. Each point represents a predictor’s coefficient in one language, with the large point showing the mean across languages. Larger coefficient values indicate a greater effect of the predictor on acquisition: positive main effects indicate that words with higher values of the predictor tend to be understood/produced by more children, while negative main effects indicate that words with lower values of the predictor tend to be understood/produced by more children; positive age interactions indicate that the predictor’s effect increases with age, while negative age interactions indicate the predictor’s effect decreases with age.

Correlations of coefficients estimates between languages. Each point represents the mean of one language's coefficients' correlation with each other language's coefficients, with the black line indicating the overall mean across languages. The grey region and dashed line show a bootstrapped 95\% confidence interval of a randomized baseline where predictor coefficients are shuffled within language.

Correlations of coefficients estimates between languages. Each point represents the mean of one language’s coefficients’ correlation with each other language’s coefficients, with the black line indicating the overall mean across languages. The grey region and dashed line show a bootstrapped 95% confidence interval of a randomized baseline where predictor coefficients are shuffled within language.

Estimates of coefficients in predicting words' developmental trajectories (as described in Figure 2), with separate models for each lexical category.

Estimates of coefficients in predicting words’ developmental trajectories (as described in Figure 2), with separate models for each lexical category.